Traditionally (since Illiger, 1811) the category or rank of "Order" has been used for Sirenia. In 1997 McKenna and Bell, following cladistic classification, proposed a new category – "Infraorder" for Sirenia, in the "Suborder" Tethytheria McKenna, 1975, "Order" Uranotheria McKenna and Bell, 1997. For ‘stability’ I retained the ordinal category, even though infraorder category conveys a cladistic message. For thorough index, complete synonymy, and bibliography of Sirenia, see Domning (1996).